A growing trend within the electrical device industry is to enable previously stand alone electrical devices, such as sensors and lighting control devices, to communicate with each other over some type of communications network. Previously, sensor, switch and control devices communicated using point to point connections. Nowadays, manufacturers are building into these devices communication means to enable them to communicate over local area networks (LANs). A variety of systems are currently commercially available which electrical device manufacturers can integrate into their products to enable them to communicate over a network.
One such system is the CEBus system which has been made an EIA standard, known as the EIA 600 standard, which was originally developed by Intellon Corp. A second system is the LonWorks system commercially available from and developed by Echelon Corp. Both the CEBus and LonWorks systems specify physical and link layer means for communicating over a variety of different media including power line, coaxial cable, fiber optic cable, radio frequency (RF), infrared (IR) and twisted pair cable.
In connection with nodes adapted to operate in the LonWorks system, there are three well defined states a LonWorks node can be in at any time. The three standard node states that a Neuron chip can be in will now briefly be described. For a more in depth description of the various node states, the reader is directed to the Neuron C Reference Guide and the Neuron C Programmer's Guide. The following applies to the Neuron IC family, including the 3120 and 3150 chip families manufactured by Motorola, Inc., Schaumburg, Ill.
1. Applicationless State
In this node state, the Neuron chip does not have an executable application program stored in memory, i.e., with the 3150, in either on or off-chip memory and with the 3120 in on chip memory only.
The Neuron chip also cannot communicate with other nodes in the network. However, an application can be installed in several ways: (1) LonBuilder, source code (.nc) or executable file (.nxe) are needed (2) NodeBuilder, source code (.nc) or executable file (.nxe) are needed (3) a 3120 family programmer and executable file (.nxe) are needed (4) a memory IC programmer for a 3150 application and an executable file (.nxe) are needed or (5) a network management tool and executable file (.nxe) are needed.
In addition, in the applicationless mode, the Neuron chip cannot process any instructions supplied by accompanying hardware or software.
In this node state, an LED connected to the service pin of the Neuron chip will be steady on.
2. Unconfigured State
In this node state, the Neuron chip has an executable application program stored in its memory, i.e., with the 3150, in either on or off-chip memory and with the 3120 in on chip memory only.
The Neuron chip cannot communicate with other nodes in the network. However, the Neuron chip can process instructions supplied by accompanying hardware and/or software.
Further, a new executable application program can be installed. In a LonWorks system a node will be considered in a configured state once an application is installed.
In this node state, an LED connected to the service pin of the Neuron chip will flash at a rate of 1/2 Hz.
3. Configured State
In this node state, the Neuron chip has an executable application program stored in its memory, i.e., with the 3150, in either on or off-chip memory and with the 3120 in on chip memory only.
Further, the Neuron chip can communicate with other nodes in the network after it is properly bound utilizing a suitable network management tool and a .XIF definition file.
In addition, the Neuron chip can also process any instructions provided by accompanying hardware and/or software. Also, a new executable application program can be installed on the node.
In this node state, an LED connected to the service pin of the Neuron chip is off.
Sometimes it is desirable to be able to place a node in the unconfigured state. This may occur at the time of installation or at any time during the normal operation of the node. One way of placing a node in the unconfigured state is to connect a switch to one of the I/O pins provided on the Neuron chip. Under suitable program control, the position of the switch can be periodically sensed and the node placed in the unconfigured state in accordance thereto. The problem with this approach is that the application software needed to perform this function may be located external to the Neuron chip. The application software will not run when the Neuron chip is in the applicationless mode state or if the application software located externally is not running. In addition, when the Neuron chip is placed in the unconfigured state, the application software stops running and all communications via the I/O pins ceases.
When the Neuron chip is this state, i.e., unconfigured or applicationless, the service pin must be grounded internally so that an application can be installed and/or the Neuron chip can be configured. Typically, this can only be accomplished while the electrical device is opened but yet still plugged into the electrical wall socket.
Further, if the application software located externally to the Neuron chip is not running, then the Neuron chip cannot receive messages from any of the I/O pins.
Other prior art methods of placing a node in an unconfigured state function only during chip power up or a reset and will not permit the node to be placed in the unconfigured state at any arbitrary time.